This work reports the effect of current density on the grain size and surface morphology of electrodeposited platinum nanowires. Platinum (Pt) nanowires were fabricated by a galvanostatic electrodeposition method in a nanoporous anodic aluminum oxide (AAO) template with different current densities. The grain size and surface morphology of the Pt nanowires were studied by field emission scanning electron microscopy (FE-SEM), transmission electron microcopy (TEM), and X-ray diffraction (XRD). The experimental results showed that the surface of the Pt nanowires became rougher and the grain sizes became larger when the deposition current density was increased. Both direct current (DC) and pulse current (PC) can be used to fine tune the surface roughness of the nanowires. Based on the experimental observations, a growth mechanism of Pt nanowires was proposed based on progressive nucleation and crystallization. The relationship between the surface morphology of the Pt nanowires and electrochemical sensing behavior toward H2O2 detection was investigated. (C) 2014 The Electrochemical Society. All rights reserved.